A New Species and Four New Recorded Species of Naididae (Annelida: Oligochaeta) from Korea

This taxonomic study investigates marine tubificids, with a focus on the genera Smithsonidrilus, Heterodrilus, Limnodriloides, and Tubificoides and presenting a new species, Heterodrilus koreanus n. sp., discovered in the around Ulleungdo and Dokdo Islands in the East Sea of the Republic of Korea. The new species, Heterodrilus koreanus n. sp., is characterized by a very long and slender atrium with prostate glands attached to the ventral side, with indistinct ducts and large round ampullae in the spermathecae. The four recorded species are: H. pentcheffi Erseus, 1981, Limnodriloides anxius Erseus, 1990, Smithsonidrilus exspectatus Erseus, 1993, and Tubificoides heterochaetus Michaelsen, 1926. This study not only enhances our comprehension of the intricate morphology within these genera but also contributes to the broader understanding of marine oligochaetes, particularly in the Korean marine ecosystem.